What does the X mean on the light? Donna Post October 27, 2016 19:48 Updated Follow Design feature-helps show where the on/off button is. It is also how to adjust through the different modes Related articles How do I charge my light? How do I know if it’s a set or not? How do I know if the light will fit my bicycle? What is COB? Are Kryptonite front and rear lights waterproof? Comments 0 comments Article is closed for comments.